TWI239434B - Method and apparatus of detecting aberrations with an optical system, lens aberration monitor and device manufacturing method - Google Patents

Abstract

A method of detecting aberrations associated with a projection lens utilized in an optical lithography system. The method includes the steps of forming a mask for transferring a lithographic pattern onto a substrate, forming a plurality of non-resolvable features disposed on the mask, where the plurality of non-resolvable features are arranged so as to form a predetermined pattern on the substrate, exposing the mask using an optical exposure tool so as to print the mask on the substrate, and analyzing the position of the predetermined pattern formed on the substrate and the position of the plurality of non-resolvable features disposed on the mask so as to determine if there is an aberration. If the position of the predetermined pattern formed on the substrate differs from an expected position, which is determined from the position of the plurality of non-resolvable features, this shift from the expected position indicates the presence of an aberration.

Description

1239434 A7 B7

The present invention relates to the detection of aberrations associated with optical systems (such as projection systems and / or illumination systems) used in lithographic projection devices, and more particularly relates to semiconductors (and other ) Design, layout, and application of aberration monitoring structures used to monitor the effectiveness of the optical system during manufacturing. The lithographic projection apparatus usually comprises:-an irradiation system for supplying an irradiation projection beam;

-A support structure for supporting a pattern member, the pattern member generating a pattern of the projection beam according to a desired pattern;-a substrate platform for supporting a substrate; and _ a method for projecting a pattern beam onto the substrate target Position projection system. Order

The term “pattern component” used here should be interpreted as a component that can be used to provide the incident light beam and the cross-section of the pattern. It conforms to the pattern that you want to create at the target position of the substrate. There is a noun, light valve ". In general, the pattern corresponds to a special functional layer within the component produced at the target, such as an integrated circuit or other component (see below). Such pattern members include:-A photomask. The concept of photomask is well-known in lithography, and it includes two types of photomasks like binary, alternating phase shift, and attenuation phase shift, as well as various mixed photomask types. The placement of the reticle in such beams will selectively transmit (if a reticle) or reflect (if a reflective reticle) the light shining on the reticle according to the pattern on the reticle. As far as the photomask is concerned, the supporting structure is usually a photomask platform, which ensures that the photomask can be supported at the desired position of the incident light beam. -4- This paper is like the Chinese National Standard (CNS) A4 specification ( 21〇X 297 public director) A7 B7 1239434 V. Description of the invention (2 and if necessary, it can be moved relative to the beam.-A programmable mirror array. An example of such a device is an adhesive telescopic (ViSC〇 elaStiC) matnx-addressable surface of the control layer and reflective surface. The basic principle of such devices is (for example) the addressing area of the reflective surface will reflect incident light into diffracted light, while the unaddressed area The incident light will be reflected as non-diffractive light. With proper filtering, the non-diffractive light will be passed through the reflected beam, leaving only the diffracted light; in this mode, the beam will be addressed according to the addressable surface of the matrix The pattern forms a pattern. The required momentary address can be performed using appropriate electronic components. More information about such mirror arrays can be taken from, for example, US patent US 5,296,89uUS mu93 Here, as for the programmable mirror array, the support structure can be embodied as a frame or platform, for example, it can be fixed or moved as required.-A programmable LCD array. Such a structure Examples are proposed in U.S. Patent 1; 3, 5,229,872, which is incorporated herein by reference. As mentioned above, the support structure in this example can be embodied as a framework or platform, for example, can be fixed or For the sake of simplicity, in the following content, in some positions, the examples of using the mask and the mask platform will be specifically explained; however, the principles discussed in these examples can be based on the content of the pattern members proposed above. Found in the lithographic projection device can be used, for example, in the manufacture of integrated circuits. In such examples, the pattern member can generate a circuit pattern that matches the individual layers of the IC, and the pattern can be mapped on the painted Previous layer of photosensitive material (at -5- this paper size applies to China National Standard (CNS) A4 specifications (210 X 297 mm)

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1239434 A7 B7 5. Description of the invention (3) Etchant) The target position (for example, including one or more crystal grains) on the substrate (silicon wafer). Generally speaking, a single wafer will contain adjacent target parts, which are irradiated through the projection system one at a time to the entire network. In the current device, patterning is performed using a mask on a mask platform to distinguish between different machine types. In one of the lithographic projection devices, each target position is irradiated by exposing a positive mask pattern to the target position. This type of device is generally called a wafer stepper. In the alternative device, a general step is a step-and-scan device. The irradiation of each target part is performed progressively in a predetermined reference direction (" scan " direction) under the projection beam. Scan and simultaneously scan the substrate platform in a direction parallel to or in the opposite direction; because, usually, the projection system has a magnification factor (usually < 1), so the speed V of scanning the substrate platform is to scan the mask platform M times the speed. More information on the lithographic devices described herein can be found in US 6,046,792 ', which is hereby incorporated by reference. In such a manufacturing process using a lithographic projection device, a pattern in a photomask (or other pattern member) is mapped onto a substrate at least partially covered with a photosensitive material (resist). Prior to this mapping step, the substrate is subjected to various procedures, such as priming, resist application, and soft baking (SOBake). After the exposure, the substrate is subjected to other procedures such as post-exposure bake (PEB), development, hard bake, and mapping feature measurement / inspection. This program is used as a basis for patterning of individual layers of a device ', such as an integrated circuit (1C). Then such a patterned layer will undergo various procedures such as etching, ion implantation (doping), metallization, oxidation, chemical-mechanical polishing, etc. All procedures are intended to complete a -6-1239434 A7 B7 5 2. Description of the invention (4) Other layers. If several layers are needed, the entire process, or its changes, must be repeated for each new layer. Finally, an array of devices is presented on the substrate (wafer). These devices are then separated from each other using techniques such as dicing or sawing, so individual devices can be mounted on a carrier, connected to pins, and so on. Further information on such procedures can be found in "Microchip Fabrication: A Practical Guide to Semiconductor Processing" by Peter van Zant, third edition, published by McGraw Hill Publishing Co. in 1997 ISBN 0-07-067250-4— Obtained from the book. For the sake of simplicity, the projection system will hereinafter be referred to as the n-lens π; however, this proper term should be generally interpreted as including various types of projection systems, including, for example, refractive optical systems, Reflective optical systems, and catadioptric systems. The illumination system also includes elements that operate according to any design pattern to guide, shape, or control the illumination projection beam, and such elements are also referred to below as '' lens". In addition, the lithographic apparatus may be of a type having two or more substrate platforms (and / or two or more photomask platforms). In this type of `` multi-stage '' device, the additional platform can be used simultaneously, with preparation steps on one or more platforms, and one or more other platforms used as exposure. For example, a two-stage lithography device is used in It is described in US 5,969,441 and WO 98/40791, which are hereby incorporated by reference. The current state of IC manufacturing requires a lithography program to provide the pattern feature line width close to one-half of the exposure wavelength. For a 150nm device, KrF excimer laser (DUV; 248nm) is usually selected as the exposure. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 1239434 A7 B7 V. Source of invention description (5). Recent research and development can already use KrF excimer lasers in 130nm devices. This can be achieved using multiple resolution enhancement techniques (RET), such as attenuated phase shift masks (attPSM) and off-axis (off -axis) illumination (ΟΑΙ), combined with optical proximity correction (OPC) technology. A shorter exposure wavelength can be used instead of the above technology , Such as an ArF excimer laser with a wavelength of 193 nm, or using a lens with an ultra-high digital aperture (NA), such as NA = 0.8 or larger. However, these alternative technologies require a large capital investment in new devices And, if feasible, generally want to delay such expenditures. Therefore, integrated component manufacturers generally want to get the most out of existing DUV systems before switching to replacement equipment. Regardless of what is used in the manufacturing process Excimer lasers, manufacturing devices with critical dimensions of 150nm or less require near-diffraction-limited lenses used in the manufacturing process to have no aberrations. As is well known, aberrations can be Caused by various sources, such as defective lenses, or aging lasers, the frequency of their beams has shifted from the desired value. Therefore, it is desirable to check the lens performance before the device (in other words, verify the lens), and then during use ( For example, during the IC manufacturing process) monitor the lens performance. During the lens manufacturing process, the lens performance can be interfered with A complete test is performed interferometrically. Usually, the lens is first verified in the factory, and then re-verified when it is first installed in the field. A method commonly used to verify the lens is to print the wafer and then measure the minimum feature width, or Critical Dimension (CD). During the verification process, the paper size will apply to the Chinese National Standard (CNS) A4 (210 X 297 mm) 1239434 A7 B7. 5. Description of the invention (6) Measurement "vertical "And" horizontal "features (in other words, features extending in two orthogonal directions on the substrate plane, such as along the X and Y axes). In some instances, CDs with 45 degree features are also measured. To check the effectiveness of the lens, a sufficient number of CD measurements must be made throughout the exposure. The results of the CD measurements are then analyzed to determine if the lens's performance is acceptable. Although the CD measurement method provides a method for evaluating lens performance, it is not a simple task to correlate CD data with the "signature" of lens aberrations. Therefore, efforts have been made to directly observe lens aberrations For example, "Identifying and Monitoring of Lens Aberrations in Projection Printing" by Toh et al., SPIE Vol. 772 — In the book, ρ · 202 · 209 (1987) makes it possible to explain a larger measurement of approximately 0.2 λ Method of the effect of lens aberrations, where λ is the exposure wavelength. However, in today's near-diffraction-limited optical devices, most of the aberrations are around 0.05 λ or less. In terms of 130nm characteristics, when using a KrF exposure source, the 0.05 λ lens aberration will be transformed into an error of 12.4nm. Therefore, if the error range of the feature CD (in other words, the error tolerance value) is assumed to be ± 10% of the target feature width, the error of 12.4nm is almost the error range of the entire CD. In "Effects of Higher-Order Aberrations on the Process Window" by Gortych et al., SPIE Vol. 1463-book, ρ · 368_ 381 (1991) shows that higher-order lens aberrations may cause lithographic processes The window deteriorated. Unfortunately, this high-lens aberration is very difficult to remove after the lithography system is assembled. In the book `` Impact of Lens Aberration on Optical Lithography, '' by Brunner, INTERFACE 1996 Proceedings, ρρ; μ27 (1996) uses simulations to explain from several first-order transmissions. 9- This paper scale applies to China National Standards (CNS) A4 specification (210 X 297 mm) 1239434 A7 B7 V. Description of the invention (7) Negative effect of near-wavelength characteristics due to mirror image difference. In particular, when using the attenuated PSM, coma aberrations can be observed by examining how the contact point characteristics are printed. It is also known that lens aberration can be balanced by custom off-axis illumination. Efforts have been made to measure various lens aberrations to achieve better CD control. In the book "Measurement of Lens Aberrations Using an In-Situ Interferometer Reticle" by Farrard et al., Advanced Reticle Symposium, San Jose, CA. (June 1999) proposed that in-situ interference can be used. Interferometer reticle directly measures lens aberrations. According to Farrar's argument, lens aberrations of up to 37 Zernike can be inferred. Although Farr claims that the method is accurate and repeatable, it includes Hundreds or thousands of registration types of measurement methods (in other words, measuring the offset related to the expected feature position). Therefore, although Farrar's method is accurate and repeatable, it requires complicated measurements, so it is clear that this method is very It is time consuming and therefore may not be suitable for a manufacturing-driven environment. In addition, it is understandable that lens aberrations must be recorded over time for various reasons (for example, regular preventive maintenance can be performed in the system). Therefore, It is important to regularly monitor lens performance, so Fanrar's method requires Measurement and calculation of quantities are not practical. Therefore, there is a need for a method that can monitor lens aberrations directly from printed product wafers. To achieve this goal, Dirksen et al. (See, for example, PCT patent application WO 0). 〇 / 3 1592) proposed a method for monitoring lens aberrations directly from printed wafers. According to Dirksen's method, the lens monitoring includes the marking line -10- This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 (Mm) 1239434 A7 B7 V. Description of the invention (8 Simple circular feature. More specifically, the circular feature is etched to the chromeless of the graticule glass substrate. The depth of the engraving is usually / 2. The diameter is approximately (also / NA), where NA is the digital aperture of the projection lens. According to Dirksen's argument, this method has been proven to be effective. In addition, the structure is quite simple and small enough to be easily placed throughout the exposure In the range, there are also some questions about the lens aberration monitoring using Dirksen. First, the depth of the lens monitoring feature on the reticle must be etched to about the wave One and a half long. For special-purpose masks, it is not a problem to use additional (or special) mask process steps to make such features. However, for production line types, such as double yellow labels Line or attPSM, requiring additional photomask process steps for monitoring is an expensive and time-consuming process. Alternate PSM (altPSM) or non-yellow PSM (CLM) also requires this additional photomask process step. In addition, when confronting the 7Γ · phase, because Dirksen monitoring must produce different etching depths on the quartz substrate, special etching time is required and must be performed separately. A second problem with Dirksen lens monitoring is that it is difficult to prevent phase errors due to the quartz etching process during the mask formation. More specifically, referring to Figure 1 (a) -1 (f) (where S represents a quartz mask substrate), for a deteriorated phase error, the quartz etching process will produce a beveled shape on the mask, As shown in Figure 1 (a). In such examples, the Dirksen monitor loses its sensitivity to show any possible lens aberrations. However, if there is no phase error on the mask, as shown in Fig. 1 (d), the Dirksen monitoring can effectively detect lens aberrations. Figures 1 (b) and 1 (e) are shown in Figure 1 (a) -11-This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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The foot-tilt '' Dirksen monitor structure and the "ideal" cross-section of the printed resist pattern produced by the structure in Fig. 1 (d) are monitored with ^^ ⑶. It should be noted that the printing conditions used to make resist shapes in ®1 (b) and 1 (e) are as follows: · With 0.8 cycles of adhesion to + 〇1Vm defocus (de_f〇cus) of 0.68NA, A Shipley UV6 resist with a thickness of 4 is used on an organic BARC (AR2) over a polycrystalline silicon wafer. This simulation will produce + 0.025 coma at y & y (27 and 28 zenik). When the ring-shaped resist pattern formed by the Dirksen monitoring structure is examined in more detail, as shown in the examples shown in Figures 1 (c) and 1 (f), it can be clearly seen that the inner ring of the printed resist pattern has a thinner resistance. The shape of the etch contrasts with the steep shape formed by the outer ring structure. The reason for this difference is that the outer ring resist pattern is formed by a phase change in the mask, while the inner ring resist pattern is formed without such a phase change. In particular, the inner ring resist pattern is formed by attenuation of the exposure wavelength through the center of the Dirksen monitor pattern. In other words, the two resist shapes (inner and outer rings) are formed by two different log-slopes. Differences in the shape of the resist may lead to erroneous measurements, which may cause misjudgment of the lens aberrations in question. It should be noted that a small amount of coma can be observed by the Dirksen lens aberration monitor, as shown in Figures 1 (e) and (f). In particular, the width of the ring is not the same on the left and right. It should also be noted that it is difficult to observe this coma in a "tilted" Dirksen monitor, as shown in Figures 1 (b) and 1 (c). Therefore, based on the above problems, a lens viewer is still needed to detect lens aberrations, but it will not be easily damaged due to slight defects in the mask manufacturing process. It is also hoped that the lens monitor structure is small enough to be placed in 12- This paper size applies to China National Standard (CNS) A4 specifications (210X 297 mm) 1239434 A7

V. Description of the Invention (The lens monitor can be manufactured by manufacturing the additional mask steps on or next to the wafer for on-site monitoring. Also hope that in order to solve the above-mentioned needs, the purpose of the present invention is to provide Lens age with observation lens aberration capability # ', ^ Yanmao Dianshizhai. Another lens of the present invention, the aberration analysis agency of the lens monitor, about ^ & 1 The monitor can be used to monitor and monitor. In addition, the purpose of the present invention is to make a child monitor without additional process steps, for example, during the formation of the front cover, and the transparency

The function of the monitor will not be significantly damaged by a slight defect in the early I% due to the mask mechanism. Order

More specifically, the present invention relates to a lens aberration monitor for detecting lens aberration. The monitor includes a number of features that cannot be disassembled (for example, 'located on a reticle). The plurality of non-decomposable features are used to project a preset test pattern on the substrate and then use the test pattern to detect lens aberrations. The size of the monitor must fit into the target area of the lithography device and the device map, which is equivalent to forming a device (such as an integrated circuit) on the substrate. For example, the monitor must be small enough to be installed to contain I c Patterned mask The present invention also relates to a method for observing aberrations associated with an optical system (illumination system and / or projection lens) used in the optical lithography system used in the publication. In the text, the method includes the steps of: -1¾: for the desired pattern to include a monitor having a plurality of non-decomposable features, wherein the plurality of non-decomposable features are used to form a preset when projecting the substrate. Pattern;-use the projection system to project the surveillance on the substrate; and -13- this paper size applies Chinese National Standard (CNS) A4 specification (210X 297 mm) 1239434

-Analyze the position of the preset test pattern and a number of unintended positions in the monitor to determine whether aberrations have occurred. In addition to the monitor, the desired pattern includes an element pattern, which is equivalent to forming an integrated element layer on the substrate. As explained below, if the position of the preset test pattern is different from the expected position, it is judged from the plurality of unresolvable features, and the deviation from the expected position indicates the existence of aberrations. As described in more detail below, the present invention provides significant advantages over previous techniques. More importantly, the present invention provides a lens monitor with the ability to detect very fine lens aberrations. In addition, because the overall size of the lens monitor structure is very small, the monitor structure can be placed in a large number of positions to monitor the entire exposure range. If the monitor is placed on a mask, it will not be affected by the defects in the mask formation process used to form the monitor. In such examples, the lens monitor of the present invention is suitable for on-site monitoring because the lens monitor can be formed using the same mask forming process as the production mask, so no additional mask formation is required. Process steps. Another advantage is that the effectiveness of the lens monitor is relatively unaffected by the mask process itself, the "tilted" phase edges and, "corner rounding" effects. # 、 Those who are familiar with this technique can further understand the other advantages of the present invention from the following drawings and the detailed description of the specific implementation examples of the present invention. Among them, the system shown in the figure, the inclined "Dirksen transparent Above and sectional view of the mirror image difference monitor structure. -14-

1239434 A7 B7 V. Description of the invention (12) Figure Ub) is a cross-sectional view of the printed resist pattern produced by the "diagonal" Dirksen lens aberration of Figure 1 (a) as a structure. Figure Uc) is a top view of the resist pattern in Figure 1 (b). The top and cross-sectional views of the "ideal" Dirksen lens aberration monitor structure shown in Figure 1 (d). Figure He) is a cross-sectional view of a printed resist pattern produced by the "ideal" Dirksen lens aberration monitor structure of Figure 1 (d). FIG. UO shows a top view of the resist pattern shown in FIG. 1 (e). Figure 2 (a) is a cross-sectional view of a modified Dirksen monitor structure to form a ring-like structure. Fig. 2 (b) is a one-dimensional cross-sectional spatial image of the ring-like structure in Fig. 2 (a). / Fig. 2 (c) is a cross-sectional view of a printed resist pattern produced by a ring-like monitor structure in Fig. 2 (a). An example of the structure of a lens aberration monitor according to the present invention shown in FIG. 3 (a) is shown in FIG. 3 (b) -3 (g). And examples of their printing performance. Figure 4 (a) shows the phase spectrum of the object generated by the structure of the Dirksen monitor in Figure 1. The phase spectrum shown in Fig. 4 (b) is the phase spectrum of the object produced by the "ring-like" monitor structure in Fig. 2. The phase spectrum of the object shown in Figure 4 (c) is generated by the lens aberration monitor structure in Figure 3 (a). -15-

1239434 A7 —______ B7_ V. Description of the invention (13)

Figure 4 (d) is a 1-D cross-sectional spatial image generated by the Dirksen monitor structure in Figure 1. The system shown in Fig. 4 (e) is a ^ D cross-sectional spatial image generated by the "ring-like" monitor structure in Fig. 2. The system shown in Fig. 4 (f) is based on the lens aberration in Fig. 3 (a). The 1-D cross-section spatial image produced by the monitor structure. Figures 5 (a)-5 (c) are the actual printing performance of the lens aberration monitor structure shown in Figure 3 (a). Figure 6 (a) The top and cross-sectional views of the lens aberration monitor structure shown in Fig. 3 (a), in which the photomask formation process results in an indecomposable feature with a slanted edge. Fig. 6 (a) The phase spectrum of the object produced by the lens aberration monitor structure shown in Figure 2). Figure 6 (c) is a two-dimensional spatial image of the lens aberration monitor structure of Figure 6 (a) projected by a projection lens. Figure 6 (d) The top view of the original resist pattern in Fig. 6 (a), which overlaps the structure of the lens aberration monitor printed on the wafer. The system shown in Fig. 6 (e) corresponds to Fig. 6 (a). Sectional view of the lens aberration monitor structure of the monitor structure. Figure 7 (a) -7 (d) shows the lens aberration monitor of the present invention used with 60 / attsM or double yellow mask. Device capabilities. Figure 8 (a The capability of the lens aberration monitor of the present invention for detecting lens aberrations shown in -8 (h) is shown in FIG. 9. The lithographic projection apparatus to which the present invention is applied is described in FIG. -16-

This paper size applies to the Chinese National Standard (CMS) A4 specification (210 X 297 public directors) 1239434 A7 B7 V. Description of the invention (14) In these drawings, the same features are indicated by the same reference symbols. Key component symbol description 10 Lens aberration monitor structure 12 times analytical features (or eight square features) 12a-12d features 14 Inner ring 15 Outer ring 16 (on the left side of printed OHR structure) Inside 17 (on the right side of printed OHR structure) Internal AM adjustment Component C Target part CO Concentrator Ex Illumination system IF Positioning component IL Illumination system (or illuminator) IN Integrator LA Illumination source MA Mask MT First object platform (mask platform) PB Projection beam PL Projection system W Substrate WT Second Object Platform (Substrate Platform) The following detailed description of the lens aberration monitor of the present invention is related to the lens aberration -17- This paper size applies to China National Standard (CNS) A4 (210 x 297 mm) 1239434 A7 B7 V. Description of Invention (15) itself, and method of forming the monitor. It should be noted that in order to make the present invention easier to understand, the following will detail how to use the monitor to form a ring structure on a photomask. However, it should also be noted that the present invention is not limited to such a ring structure; specifically, other shapes are also possible. Furthermore, the structures need not necessarily be formed on a reticle; they can, for example, be produced using other pattern members. From the above observations on the Dirksen monitoring, the original idea of the inventors of the present invention is that the shape of the inner ring corrosion resistance of the Dirksen monitor structure can be improved by modifying the monitor so that it presents a ring-like structure. In other words, the reduced / thinner resist shape of the inner ring of the Dirksen monitor structure can be corrected by generating a phase change at the center point of the offending structure. However, contrary to the original idea, the inventors of the present invention have determined that a phase change at the center point of the Dirksei ^ # structure does not cause a resist shape that exhibits a ring-like structure. In addition, the resulting resist shape does not substantially monitor lens aberrations. The system shown in Figs. 2 (a) -2 (c) modifies the monitor structure of 11: 1 ^ 611 to form a ring-like structure. In particular, the system shown in Fig. 2 (a) is modified by the Dirkser ^ # structure to form a ring-like structure above and in a cross-sectional view. Fig. 2 (b) is a one-dimensional cross-sectional space image of a ring-like structure in Fig. 2 (a) (where the intensity is shown). Fig. 2 (c) is a cross-sectional view of a printed resist pattern produced by the ring-like structure in Fig. 2 (a). It can be clearly seen from Figs. 2 (a) -2 (c) that the ring-like structure (the figure does not produce a ring-shaped resist shape. This is because the spatial image ratio of the monitor structure is not strong enough to form "Loop-like, corrosion-resistant structure. As a result, Figure 2 (the structure of 昀 can not be used to monitor lens aberrations in essence. It is worth noting that as long as the diameter of the monitor structure is in the / NA range, the front Methodology

1239434 A7 —_____ B7 I. Description of the Invention (16) — " ~ 'is quite accurate. For a larger diameter, the ring-like design of Fig. 2 (a) may print a ring-like resist pattern. However, when the diameter exceeds i / NA, the effect of the lens aberration monitoring is reduced. In view of the foregoing, one of the main objects of the present invention is to provide a lens aberration monitor having an effective diameter in the range of N / A, which generates a spatial image with a logarithmic slope sufficient to sufficiently sense and represent the lens aberration. Fig. 3 (a) shows an example of a lens aberration monitor structure according to the present invention. As shown in the figure, the lens aberration structure 10 refers to the Octad Halftone Ring (OHR), and the screen structure of one resolution includes multiple resolution features 12. A detailed discussion of the formation of the secondary screen structure is, for example, proposed in European Patent Application No. EP 0 980 542. In the specific example shown in Fig. 3 (a), all the shapes of the stencil structure of this time are circular, and each feature 12 is square. It is to be noted that the aberration monitor structure 10 of the present invention is not limited to such a shape. Undoubtedly, the entire shape of the screen structure 10 may not be circular, and the shape of each feature 12 may not be square. It should be noted that the square secondary resolution feature 1 2 is likely to become rounded corners due to the characteristics of the mask process in actual design. Referring to FIG. 3 (a), the dimensions of the individual features 12 and the intervals between the features 12 are as follows. In a specific example, the size s L of each side of the square feature is approximately 0.3 (λ / NA) or less. It should be noted that this mask manufacturing analysis will limit the minimum size of the sub-resolution features 12. In terms of the current photomask manufacturing process, the resolution limit on a 4X photomask is about 200 nm. In a 1 X wafer scale, this is equivalent to 50 nm. For example, when using a 0.68 ΝΑ stepper and KrF exposure -19- this paper size applies Chinese National Standard (CNS) A4 specifications (210X 297 mm) 1239434 A7 ___ _ B7 V. Description of the invention (17) The size of each side of each square feature 12 may be approximately 100.12 Onm. In order to maintain the full effect of the screen, it is best that the space ES between 12 square features is less than 0.15 (λ / NA). Alternatively, the interval E S between each square feature 12 should be less than 0.15 (several / NA). In addition, the interval between each feature i 2 should be less than half the size of the side of the square feature 12. It should be noted that, as shown in Fig. 3 (a), the above-mentioned spatial conditions refer to the interval between adjacent features 12. Also note that, as shown in Figure 3 (a), the staggered offsets (XST and YST, respectively) in the X and Y directions are preferably the same. In other words, it is preferred that the features 12 that overlap the adjacent feature 12 in the X direction or the γ direction are the same. In the present specific example, the preferred interleaving compensation is preferably in the range of ¼ / 4 to 3/4 which is approximately the size of the resolution element. Finally, referring to Figure 3 (a) again, it should be noted that the farthest distance EES between the inner sides of two opposite features is along the X direction (in other words, features 12a, 12b) or the Y direction (in other words, feature 12c). , 12d), preferably approximately equal to (λ / NA). All dimensions are expressed on a 1 X wafer scale. In the specific example of the lens aberration monitor shown in Fig. 3 (a), the screen structure 10 of the present invention makes use of eight square features 12 in a ring-like format. However, as already explained, the present invention is not intended to be limited thereto. Undoubtedly, it is possible to generate and use sub-resolution screen structures that do not exhibit a ring-like shape. Because features of shapes other than squares can be used, multiple sub-resolution features other than eight can be used to form the sub-resolution screen structure. More special is' Although 1 in e-like structure (such as a pair of parallel lines) can display some types of lens aberrations (such as coma), S Η 家 鲜 (CNS) A4 specification (21GX297 public director) ~ 1 1239434 A7; ----B7 V. Description of the invention (18) Catch other types < lens aberrations and corresponding directions, so it is still desired to form one, , Like a% -like structure. In addition, because each feature i 2 is a sub-resolution, the special opening is not important. The size of the special imitation 2 and the spacing of the screens are more important. Figures 3 (b), 3 (c), and 3 (d) are examples of various structures that can be used to form the monitor structure. The differences between Figs. 3 (e), 3 (f), and 3 (g) are the T-printing performances of the monitor structures shown in Figs. 3 (b), 3 (c), and 3 (d), respectively. All exposures are performed under the same conditions, that is, in a ring ..., Ming 0.68NA (0.6 inner sigma and 0.8 outer sigma, sigma (0 is the so-called adhesion coefficient). In addition, in In each example, the coma amounts of X and γ of λ 0.05 were produced intentionally. For all three examples, the added aberration can be clearly seen from Fig. 3 (e), 3 ([) And 3 ($) were observed in the printed pattern. Figure 4b) -4 (〇 shown in the system 1 ^ 1:] ^ 611 monitor structure (Figure 1), like a ring monitor structure (Figure 2) Comparison of object spectrum and space image with the 0HR monitor structure of the present invention (Fig. 3 (a)). In these drawings, p represents the phase and the intensity is shown. More specifically, first refer to the figure 4 (a), the phase object spectrum of the Dirksen monitor shown is not symmetrical within the "NA (Digital Aperture) limit. Turning to Fig. 4 (b), the shown" ring-like "monitor has A symmetrical phase spectrum but the entire phase range is compressed. However, as explained above and shown in Figure 4 (e), the spatial landscape presented by this "ring-like" monitor structure > The image contrast is not enough, so a ring-like resist pattern cannot be printed. Turning to the system shown in Figure 4 (c), the 0HR monitor 10 presents a symmetrical phase spectrum within the limit of soil να, and all phases The range is from 0 to 36 °. When comparing the two at the printing threshold of 0.3 to 0.35 intensities, the 0hr monitor-21-I paper scale is suitable for wealth _ home scale (⑽) A4 size (21GX297 public love) -------- 1239434

The space shadow of the viewer 10 (as shown in Figure 4 (f)) and the space image generated by the Dirksen monitor (see Figure 4fH, correction—, door ^, bu, mouth 4 (d)) Not the same. However, although it is not obvious that the logarithmic slopes of the inner and outer space images at the intensity level of the a ^^^ are more balanced than OHR's current view, 、, and 构 10. This is shown by a pair of arrows in Figure 4⑷ and Figure 4⑴. The tf shown in Figs. 5 (a) and 5 (c) is the actual printing effect of the lens monitor structure 〇 shown in Fig. 3 (a). The printing conditions used to produce Figures 5 (a) and 5⑷ are the same as those described in Figures 1 (a) -1 (f). Fig. 5 (a) is a two-dimensional spatial image of the HR monitor structure 10 when projected on the projection lens (I represents intensity). FIG. 5 (b) is a plan view of the original resist pattern (in other words, feature 12) that overlaps with the HR monitor structure (in other words, the HR monitor structure is generated by the printing process). As shown in Figures 5 (a) -5 (c), even very small coma aberrations can be detected by the monitor. More specifically, in the 2-D space image of Fig. 5 (a) and Fig. 5 (b), it can be observed that coma aberration has been added to the simulation (both Z7 and Z 8 are 0.025 again). Referring to FIG. 5 (b), the aberration is shifted to the upper right by the inner ring 4 of the printed HR structure. Finally, FIG. 5 (c) is a cross-sectional view of the printed OHR structure, which shows (in the cross-sectional view) the inner portion of the left side of the printed OHR structure. The extent to which the interior 17 moves towards the middle. The shift / change in the position of each of the above-mentioned OHR structures indicates the existence of lens aberrations. In the absence of lens aberrations, the inner ring 14 of Fig. 5 (b) has the same interval as each square feature 12 used to form the OHR monitor structure 10. In addition, the intervals between the resist patterns 16 and 17 in FIG. 5 (c) and the center point are the same. -22- This paper size is in accordance with Chinese National Standard (CNS) A4 specification (21〇x 297 public love) 1239434 A7 — ______ B7 7. Description of the invention (20) ~-When using it, please note that the HR monitoring The device is printed in a scribe line or in a die to prevent interference with circuit operation, and can be measured to monitor actual lens aberrations in the corresponding exposure range. Next, lens aberrations will be used to calculate the necessary corrective actions required to minimize CD errors. Examples are not mentioned. The corrective action can be accomplished by changing the mask pattern or adjusting the exposure tool. As explained herein, the total amount of lens aberration can be determined by measuring the relative ring width or the relative offset position of the inner ring relative to a known reference structure that is not affected by lens aberrations. Another possible method is to take a SEM picture of the printed 0Hr pattern and compare it with a series of OHR patterns with known lens aberrations. Using statistical analysis, the size and type of lens aberration can be repeatedly determined. An important point about the OHR monitor of the present invention is that the performance of the monitor will not be reduced due to a defective photomask process. More specifically, if the quartz etching causes oblique phase edges on the reticle, the OHr monitor does not lose the sensitivity of lens aberration detection. The system shown in FIG. 6 (a) is formed above and a cross-sectional view of the HR monitor structure, which is formed in the illuminating mask (S represents the reticle substrate), and the reticle forming process will produce a square feature with inclined sides 12. This beveled edge is a result of the use of a defective quartz upper edge process during the mask formation. However, referring to FIG. 6 (b), it is known that the oblique quartz phase edge pattern on the reticle does not significantly affect the phase light of the object. The spectral phase of all objects is only slightly compressed (to about 350 degrees). This type of compression will slightly reduce the sensitivity of the lens aberration detection monitor. However, more importantly, even for extreme oblique phase edges, as shown in Figures 6 (c)-6 (e), only the seal -23-1239434 A7 ——; _________ B7 V. Invention Note (21) The shape of the brush resist has little effect. Therefore, the OHR monitor of the present invention provides a more versatile monitor than a Dirksen monitor. It should be noted that the printing conditions used to produce Figures 6 (c)-6 (e) are the same as those described in Figures 1 (a) -1 (f) above. As previously explained, it is desirable to use the lens aberration monitor of the present invention for on-site monitoring during production printing. In order to accomplish this, the following conditions must be met: (1) the lens aberration monitor must be manufactured using the same mask process without the need for additional processing steps; and (2) when exposed to the same exposure as the printed pattern The lens aberration monitor structure must be usable and effective when printing is performed. The OHR monitor of the present invention can satisfy both of these conditions. Figures 7 (a) -7 (d) prove that the OHR monitor of the present invention can be used in a 6% attPSM or double yellow mask. It should be noted that the printing conditions used to produce Figs. 7 (a) -7 (d) are the same as those in Figs. 1 (a) -1 (f) described above. More specifically, the top view of the resist pattern shown in Fig. 7 (a) is formed in a 6% attPSM and overlaps with the generated printed HR monitor structure. Fig. 7 (b) is a cross-sectional view of a printed 0hr monitor structure produced by the resist pattern of Fig. 7 (a). The top view of the resist pattern shown in FIG. 7 (c) is formed in a double yellow mask and overlaps with the structure of the printed OHR monitor produced. Fig. 7 (d) is a cross-sectional view of a 0hr monitor structure generated from the resist pattern of Fig. 7 (c). It can be clearly seen from Figures 7 (a) -7 (d) that the OHR monitor structure formed by 6% attPSM and the HR monitor structure formed by double yellow masks are used. -24- This paper is applicable to China Standard (CNS) A4 (210 X 297 mm) 1239434 A7 B7

Fifth, the invention can detect subtle lens aberrations (for example, 0.025 λ). For example, the inner ring 14 of the OHR monitor structure produced in Figs. 7 (a) and 7 (c) is shifted to the upper right direction and the way of the HR monitor structure shown in Fig. 5 (b). The same, so that it can effectively detect the 0.25 lens aberration added in the simulation. It is important to note that in order to ensure that the same exposure level will be used in related product patterns, for 6% attPSM and double yellow mask applications, the size of the 0HRi square 12 must be readjusted to "〇 · 35 ( Into / ΝΑ). Other 0HR design parameters remain unchanged. However, because larger square elements are used, it proves that the spacing between each square element must be readjusted to achieve the best screen effect. As explained above, the OHR monitor of the present invention is very versatile. For example, in addition to detecting coma aberrations, the OHR monitor can also detect various types of lens aberrations, as shown in Figures 5, 6, and 7 above. The ability of the HR monitor to detect lens aberrations shown in Figures 8 (a) -8 (h). It should be noted that the printing conditions used to produce Figures 8 (a) -8 (h) are the same as those described in Figures 1 (a) -1 (f) above, except for the lens aberration setting, all of which have + 0.1 μηι out of focus. FIG. 8 (a) is a plan view of a resist pattern for forming the HR monitor structure and overlapping the HR monitor structure produced by printing with a diffraction-limiting lens. The wavefront at the pupil of the projection lens of the OHR monitor shown in Fig. 8 (e) is shown in Fig. 8 (e). As shown in the figure, when the inner ring 4 and the outer ring 5 are in the expected positions, the printed HR monitor structure will indicate that the lens is essentially aberration-free. -25- This paper ruler is floating _home standard (CNS) M size (2iqχ tear public director) 1239434 A7

Fig. 8 (b) is a plan view of a resist pattern of a lens aberration monitor structure having a 005λ lens aberration of 45 degrees astigmatism at the time of printing. The wavefront at the pupil of the projection lens conforming to the structure of the OHR monitor shown in Fig. 8 (b) is shown in Fig. 8 (f). As shown, the OHR monitor structure can show the lens aberration by extending the inner ring 14 along the axis of degrees. Figure 8 (c) shows the top view of the resist pattern of the lens aberration monitor structure with χ and γ coma (27 and 28) at the time of printing, and the resulting OHR monitor Structures overlap. The system shown in Fig. 8 (g) corresponds to the wavefront at the pupil of the projection lens of Fig. 8 (Magic OHR monitor structure. As shown in the figure, the printed OHR monitor structure consists of the inner ring 4 and the outer ring 丨5 is shifted up and to the right to display the lens aberration. The system shown in Figure 8 (d) has X and γ tilts (Z2 and 23) when printing, and a lens aberration monitor structure with lens aberration. The top view of the resist pattern overlaps with the produced OHR monitor structure. Figure 8 (h) shows the wavefront at the pupil of the projection lens that conforms to the OHR monitor structure of Figure 8 (d). As shown in the figure 'The printed OHR monitor structure displays the lens aberration by shifting the inner ring 4 and the outer ring 5 down and to the left. Therefore, even the actual lens aberration may be very complicated and small. The invented OHR monitor and the latest metrology tools can analyze the potential causes of lens aberrations. It should be noted that when viewing the wavefront projected on the pupil of the projection lens of the figure, you can also clearly see Figure 8 (a ) _8 (h) The aberration of the lens identified. Figure 9 is a schematic illustration of a lithographic projection device suitable for the present invention. The apparatus comprises: -26- This paper scales applicable Chinese National Standard (CNS) A4 size (297 mm 21〇χ) 1239434

The irradiation system Ex, IL is used to provide irradiation (e.g. UV or EUV irradiation) < projected light beam PB. In this particular example, the illumination system also includes an illumination source LA; • a first object platform (mask platform) MT is equipped with a mask holder that supports a mask MA (eg, a marking line), and is connected to The first positioning member is used to accurately position the photomask relative to the PL; a second object platform (substrate platform) WT is provided with a substrate holder that supports a substrate w (such as a coated silicon wafer), And is connected to the second positioning member to accurately position the substrate relative to the PL; a projection system ("lens,") PL (such as a refractive, full-refractive or reflective optical array) is used to illuminate the mask MA The position is mapped to a target portion C of the substrate boundary (for example, including one or more dies). As described herein, the device is a conductive type (in other words, it has a conductive mask). However, in general, it is also a Is a type of reflection, for example (with a reflective mask). Exceptionally, the device can use another patterned component, such as the programmable mirror array described above. Light source LA (eg mercury lamp, excimer laser) (Or ion light source) will generate an illumination beam. This beam will be sent to the illumination system (illuminator) IL 'directly or after passing through the adjustment member, such as the beam expander Ex. The illuminator IL includes for setting The beam intensity is assigned to the adjusting member AM of the outer and / or inner ring ranges (commonly referred to as σ-outer and σ-inner, respectively). In addition, it usually includes various other elements, such as an integrator IN and a condenser Device C 0. According to this method, the light beam pb will be irradiated on the photomask M A with the desired uniformity and intensity distribution on its cross-section. -27- This paper size applies the Chinese National Standard (CNS) A4 specification 210 X 297 mm) 1239434 A7 B7 V. Description of the invention (25) Then the beam PB will touch the mask MA supported on the mask platform MT. After passing through the mask MA, the beam PB will pass through the lens PL, which will The light beam PB is focused to the target portion C of the substrate W. With the second positioning member (and the interferometer measurement member IF), the substrate platform WT can be accurately moved, and thus different target portions C in the path of the light beam PB can be positioned. Ground, when the mask MA is mechanically taken out from the mask library, or during scanning, the first positioning member can accurately position the mask μα in the path of the beam PB. Generally speaking, the movement of the object platform MT, WT uses long-stroke modules (coarse positioning) and short-stroke modules (fine positioning), which are not explicitly shown in Figure 9. However, as for the wafer stepper (as opposed to a step-and-scan device), the reticle platform MT may be connected to a short-stroke starter, or it may be fixed. The description device can be used in two different modes:-In the step mode, the mask platform MT is basically kept stationary, and the entire mask image is projected once (in other words, "flash") to the entire target portion C . Then the substrate platform WT will move in the X and / or y direction so that the light beam PB can illuminate different target portions c;-in the scanning mode, it is basically the same situation, except that the target portion C is not known once. Instead of exposure, the mask platform MT can be moved at a speed u in a known direction (the so-called “scanning direction,” for example, y-universal), so that the projection beam pB can be at At the same time as scanning j on the mask image, the substrate platform wt moves at the same time in the same or opposite direction at a speed v = Mv, where the magnification of the M lens PL (usually, 1/4 or) moves. In this way, a larger target portion c can be exposed, but -28-

1239434 A7 B7 5. The invention description (26) does not affect the resolution. The invention can, for example, be used to check aberrations in the illuminator IL and / or the projection system PL of the above-mentioned device. As mentioned above, various changes can be made to the exemplary embodiment of the OHR monitor of the present invention. For example, although the exemplary OHR monitor structure has a circular shape, it is no doubt that other shapes are also possible. In addition, the individual features used to form the OHR monitor structure may not be square. In addition, the OHR can be used in all types of reticle, for example, double yellow, attPSM, alternating PSM, and colorless PSM. Because the OHR design indicates that such structures and feature intervals are very sensitive to lens aberrations, the design size of the OHR can be used as a reference for "forbidden" design rules in integrated circuit design. As a result, the circuit characteristics become less affected by lens aberrations. This is very important for the design of the Billion Circuit or Library Circuit, which can strengthen / improve the CD control. As mentioned above, the OHR monitor of the present invention provides important advantages over this prior art. More importantly, the present invention provides a lens monitor capable of detecting very fine lens aberrations, which is not affected by defects in the process of forming a mask for forming the monitor. In addition, the lens aberration monitor of the present invention is suitable for on-site monitoring because the lens monitor can be formed using the same mask formation process required to form a production mask, and therefore no additional mask formation process steps are required. In addition, because the overall size of the lens monitor structure is very small, the structure can be placed in many positions to monitor the entire exposure range. There is another advantage because the structure of the lens aberration monitor of the present invention is advantageous. 29- This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) 1239434 A7 B7 V. Description of the invention (27 ) Use the sub-resolution feature. The actual shape and size of the feature are not very important, so the lens aberration monitor has a very good effect in detecting aberrations in practical applications. Finally, it should also be noted that although the lithographic projection device in the manufacture of integrated circuits can be referred to in the previous description, it should be understood that such devices have other applications. For example, it can be used in the manufacture of integrated optical systems, magnetic memory guidance and detection patterns, liquid crystal display panels, thin film magnetic heads, and the like. Those skilled in the art will understand that in the content of this alternative application, the proper nouns used in this article, "marking lines" or "wafers", can be more commonly used, and masks "Or, substrate" instead. In this case, the proper terms "irradiation" and "beam" are used to cover all types of electromagnetic radiation, including ultraviolet radiation (such as wavelengths 365, 248, 193, 157 or 126nm) and EUV (extreme ultraviolet radiation, for example, a wavelength range of 5-20 nm). Although certain specific examples of the present invention have been disclosed, it should be noted that the present invention can be used for other special features without departing from the spirit or essential characteristics of the present invention. The foot type is specific. Therefore, the present invention is merely an explanation and not a limitation in all aspects. The scope of the present invention is indicated by the scope of the appended patent application rather than the foregoing description. Significance is included in it. 30- This paper size applies Towel ® ® Home Standard (CNS) A4 specification (21G X 297)

Claims (1)

1239 | Catch Patent Application No. 28361 Replacement of Chinese Patent Application Scope (August 1993) Patent claim range 8 8 88 * 'AB c D 9a. A method for detecting aberrations of an optical system used in a lithographic projection device' The lithographic projection device includes: An illumination system for providing a projection beam A support structure for supporting a pattern member, the pattern member patterning the projection beam according to a desired pattern; a substrate platform for supporting a substrate; and a method for projecting a pattern beam onto the substrate The projection system on the target part, the optical system includes at least one of an illumination system and a projection system. The method includes the steps of: providing the desired pattern to include a 1-view device having a plurality of non-decomposable features, ^ The plurality of non-decomposable features are used to form a preset test pattern when projected on the substrate; using the projection system to project the monitor onto the substrate; and analyzing the position of the preset test pattern in the monitor and Multiple locations where features cannot be resolved to determine if there is an aberration. 2. The method according to item 1 of the scope of patent application, wherein any one of the plurality of non-decomposable special desires is equipped with a square cross-section structure, and the plurality of non-decomposables are placed relative to each other to form a substantially circular shape. . 3. The method according to item 2 of the scope of patent application, wherein any one of the plurality of non-decomposable features has a side length of up to 0.30 (λ / ΝΑ), and is the wavelength of the projection beam, and Ν Α The digital aperture of the projection system. 4 The method according to item 3 of the scope of patent application, wherein the interval between adjacent edges of adjacent indecomposable features is at most 0.15 (λ / NA). 1239434 8 8 8 8 A B c D 5 • If the method of any one of items 1 to 4 of the scope of patent application, the preset test pattern is roughly a circular pattern. 6. The method as claimed in any one of claims 1-4, wherein, in addition to the monitor, the desired pattern includes an element pattern corresponding to an integrated element layer formed on the substrate . 7. The method according to any one of claims 1 to 4, wherein the first group of multiple non-decomposable features overlap with each other in the χ_ direction, and the second group of multiple non-decomposable features are in The y_ direction overlaps, approximately the father is in the X-direction, and the X-direction overlap is approximately equal to the Y-direction overlap. 8. The method according to any one of claims 1-4, wherein the pattern structure is used as a photomask. 9. The method according to item 8 of the scope of patent application, wherein any one of the plurality of unresolvable features is a 7? -Phase shift element. 10. The method according to item 8 of the scope of patent application, wherein the mask is one of a 6% attenuation phase shift mask and a double yellow mask. 1 1. A device for detecting aberrations of an optical system used in a lithographic projection device, comprising: an irradiation system (Ex, IL) for providing an irradiated projection beam; and a support for a photomask ( (MA) a mask platform (MT); a substrate platform (wt) for supporting the substrate (w); and a projection system (PL) for projecting a pattern in the mask onto a target portion of the substrate, The optical system includes at least one of an illumination system and a projection system, and the -2-this paper size applies to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 8 8 8 8 AB c D 1239434 The structure includes a mask plate carrying a monitor pattern. The monitor pattern includes a plurality of indecomposable features placed on the mask plate. The plurality of indecomposable features are used to form a preset on the substrate. Test pattern, the preset pattern is used to detect the aberration. 12. The device according to item 11 of the scope of patent application, further comprising an element pattern placed on the mask flat plate, which corresponds to the integrated element layer formed on the substrate. 1 3. A method for manufacturing a component, comprising the steps of: (a) providing a substrate at least partially covered with a photosensitive material layer; (b) providing an irradiated projection beam using an irradiation system; (c) using a pattern member to The cross-section of the projected beam imparts the pattern; (d) projecting the illuminated pattern beam onto the target portion of the photosensitive material layer using a projection system, wherein aberrations are performed before using the integrated element pattern of step (d) The monitoring step includes the steps of:-providing the pattern of step (c) to include a monitor having a plurality of non-decomposable features for forming a preset test when projecting on the substrate Patterns;-project the monitor onto the substrate using the projection system; and-analyze the positions of the preset test patterns in the monitor and the positions of the multiple non-decomposable features to determine at least one of the illumination system and the projection system Whether the system has aberrations. 14. A lens aberration monitor to detect lens aberrations, the monitor comprising: a photomask to transfer a lithographic pattern onto a substrate; and -3- the paper size applies to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 8 8 8 8 AB c D 1239434 --- VI. Patent application scope μ Xi person / person analysis special desire, it is formed on the photomask, the multiple times analysis special release million, A predetermined pattern is formed on the substrate and the predetermined pattern is used to detect lens aberrations. Among the features of the multiple sub-resolutions, none are imaged separately on the substrate. 15. If the lens aberration monitor of item i 4 of the scope of patent application, each of the multiple sub-analytical features is a square cross-sectional structure, and the multiple sub-analytical features form a circular shape relative to each other, Each of the multiple sub-analytical features has a square cross-section structure, and the length of each side is 0 · 30 (λ / NA) or less, where the wavelength of the light source used for imaging on the substrate, and ΝΑ It is a digital aperture of the objective lens used for imaging on the substrate, which is a lens aberration monitor of item No. 14 of the patent scope, each of which has a number of sub-analysis features: a phase shift element. 1 7 · A method for forming a lens aberration monitor for detecting lens aberration, the method includes the following steps: opening a photomask to transfer a lithographic pattern onto a substrate; and forming a plurality of photomasks on the photomask Multiple sub-analysis features, the multiple sub-analysis features forming a predetermined pattern on the substrate for detecting lens aberrations, wherein the multiple sub-analysis features are not separately imaged on the substrate. 1 8. The method of forming the aberration monitor of the lens according to item 7 of the patent application, wherein each of the multiple sub-analytical features is a square cross-sectional structure, and the multiple sub-analytical features are relative to each other. Form a circle, each of which has a plurality of sub-analytical features with a square cross-sectional structure, and the length of each side is 0.30 (also / nA) or less, of which is used for -4- paper The scale is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 8 8 8 8 AB CD 1239434, the wavelength of the light source imaged on the substrate for patent application, and NA is the objective lens used for imaging on the substrate Digital aperture. 19. The method for forming an aberration monitor of a lens according to item 17 of the patent application, wherein each of the multiple sub-analysis features is a 7Γ-phase shift element. -5 This paper size applies to China National Standard (CNS) A4 (210X297 mm)